The present invention relates to silica gel supported bis-cinchona alkaloid derivatives and a preparation method and use thereof. More particularly, the present invention relates to silica gel supported bis-cinchona alkaloid derivatives of the formula III by chemically reacting formula I as a chiral monomer with silica gel of the formula II. The present invention also relates to the use of the formula I as a catalyst in synthesizing optically-active vicinal diols by asymmetric dihydroxylation reaction of olefins.
The asymmetric dihydroxylation of olefins using catalytic amounts of osmium tetraoxide or potassium osmate dihydrate in the presence of cinchona alkaloid derivatives allows access to a wide variety of optically pure vicinal diols [(a) Johnson, R. A. and Sharpless, K. B. Catalytic Asymmetric Dihydroxylation. In Catalytic Asymmetric Synthesis; Ojima, I., Ed.; VCH publishers: New York, 1993; pp 227-272, (b) Chem. Rev., 1994, 94, 2483-2547, (c) Tetrahedron Asymmetry, 1992, 3, 1317-1349]. However, there are limitations to performing the catalytic AD reaction in synthesizing vicinal diols on a large scale due to the toxicity and high cost of osmium tetraoxide or potassium osmate dihydrate and the cinchona derivatives. By employing the heterogeneous catalytic systems, it was expected to cost-down by using osmium tetroxide and bis-cinchona alkaloids repetitively. To this end, several polymer-bound cinchona alkaloid derivatives have been developed. However, these heterogeneous catalytic systems did not have practical applicability since most of the polymers require complicated synthetic manipulations and, moreover, their catalytic efficiency and enantioselectivity were much worse than those of the homogeneous catalytic systems [(a) Tetrahedron Lett., 1990. 31, 3003, (b) Tetrahedron Lett., 1991, 32, 5175, (c) Tetrahedron Lett., 1992, 33, 5453, (d) Tetrahedron: Asymmetry, 1993, 4, 2351, (e) Tetrahedron Lett., 1994. 35, 6559.